Recently, with the rapid development of software, semiconductor technology and information processing technology, various information devices such as mobile phones or Personal Digital Assistants (PDAs) are gradually becoming small and realizing multifunctionality, and together with this, the importance of information storage and communication using the input of characters or the like in such an information device is gradually increasing.
However, an input device for various characters or commands in an information device that is currently being used still has too many problems to suitably cope with the above-described variation in an information environment.
That is, the most important thing in the input of characters is to promptly and accurately input desired information, and, for this operation, it is most preferable to accurately input characters using a minimum number of manipulations.
For this input operation, the most preferable input device is a structure in which separate input keys are set for respective characters, but this device is actually inefficient because more than 100 input keys, including keys for 24 phonemes for the Korean alphabet, 26 phonemes for the English alphabet, 10 numerals, and various types of symbols, are required.
Meanwhile, various types of functions, such as Moving Picture Experts Group Layer (MP3), Digital Multimedia Broadcasting (DMB), and a video call, in addition to a basic function such as a phone call, have been continuously added to recent portable mobile communication terminals.
However, in the actual condition, a wider screen and a larger input device are required to efficiently implement such complicated functions, whereas the entire size of a terminal is gradually becoming smaller.
Meanwhile, when characters are input using the above-described touch screen-type terminal, a method of inputting relevant characters by dividing part of a touch screen as an input area, by arranging a plurality of input keys in the input area and by touching the respective input keys has been used.
Such a conventional touch screen-type terminal is inconvenient in that it is impossible to arrange a plurality of input keys in the input area due to spatial restrictions.
Further, the conventional touch screen-type terminal is problematic in that, since input keys for character input must be arranged in the input area, the size of the screen is inevitably reduced.
Furthermore, in order to input characters, symbols or numerals desired to be input by a user, a method of touching respective input keys arranged on the screen is performed. However, there are problems in that since, during this procedure, the case where keys other than keys desired by the user are manipulated frequently occurs, erroneous operations occur, and in that, since respective input keys must be manipulated several times to obtain the user's desired information, an input method is complicated, and the time required for character input is increased.